Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China; State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Sci Total Environ. 2024 Aug 25;940:173667. doi: 10.1016/j.scitotenv.2024.173667. Epub 2024 May 31.
The retention and mobilization of phosphate in soils are closely associated with the adsorption of iron (hydr)oxides and root exudation of low-molecular-weight organic acids (LMWOAs). This study investigated the role of LMWOAs in phosphate mobilization under incubation and field conditions. LMWOAs-mediated iron (hydr)oxide transformation and phosphate adsorption experiments revealed that the presence of LMWOAs decreased the phosphate adsorption capacity of iron (hydr)oxides by up to ~74 % due to the competition effect, while LMWOAs-induced iron mineral transformation resulted in an approximately six-fold increase in phosphate retention by decreasing the crystallinity and increasing the surface reactivity. Root simulation in rhizobox experiments demonstrated that LMWOAs can alter the contents of different extractable phosphate species and iron components, leading to 10 % ~ 30 % decreases in available phosphate in the near root region of two tested soils. Field experiments showed that crop covering between mango tree rows promoted the exudation of LMWOAs from mango roots. In addition, crop covering increased the contents of total phosphate and available phosphate by 9.08 % ~ 61.20 % and 34.33 % ~ 147.33 % in the rhizosphere soils of mango trees, respectively. These findings bridge the microscale and field scale to understand the delicate LMWOAs-mediated balance between the retention and mobilization of phosphate on iron (hydr)oxide surface, thereby providing important implications for mitigating the low utilization efficiency of phosphate in iron-rich soils.
土壤中磷酸盐的保留和迁移与铁（氢）氧化物的吸附和低分子量有机酸（LMWOAs）的根系分泌密切相关。本研究探讨了在培养和田间条件下 LMWOAs 在磷酸盐迁移中的作用。LMWOAs 介导的铁（氢）氧化物转化和磷酸盐吸附实验表明，由于竞争效应，LMWOAs 的存在使铁（氢）氧化物的磷酸盐吸附容量降低了高达约 74%，而 LMWOAs 诱导的铁矿物转化导致磷酸盐保留量增加了近六倍，因为结晶度降低和表面反应性增加。根盒实验中的根系模拟表明，LMWOAs 可以改变不同可提取磷酸盐物种和铁组分的含量，导致两种测试土壤中近根区有效磷含量降低 10%30%。田间实验表明，芒果树行间的作物覆盖促进了芒果根分泌 LMWOAs。此外，作物覆盖分别使芒果树根际土壤中总磷酸盐和有效磷的含量增加了 9.08%61.20%和 34.33%~147.33%。这些发现将微观尺度和田间尺度联系起来，以了解铁（氢）氧化物表面上磷酸盐保留和迁移之间的微妙的 LMWOAs 介导平衡，从而为缓解富铁土壤中磷酸盐利用率低提供了重要启示。
